Explanation of TFT Blood Test Results


TFT blood tests are designed to test the functioning of the thyroid gland. They are primarily used to detect whether the thyroid is over-performing or under-performing, known as hyperthyroidism or hypothyroidism respectively. According to the American Thyroid Association, there are four blood tests that are readily available and used frequently to measure TFT results: the TSH blood test, the T4 blood test, the T3 blood test, and the free T4 blood test.

Most of the hormones that are produced by the thyroid will circulate in the blood as they are bound to proteins. A small percentage is not bound, which is referred to as “free.” For this reason, the free T4 blood test is often ordered most frequently.

When Is the TFT Blood Test Ordered?

The TFT blood tests will be ordered by a medical provider whenever the signs and symptoms of an overactive or under-active thyroid are present.

If the thyroid is over-performing, then this may result in an increased heart rate, heightened anxiety, trouble sleeping, and tremors in the hands. Some people may also experience weight loss, feelings of weakness, intermittent diarrhea, and light sensitivity. The eyes can also be affected by this condition, creating a puffiness around the orbital area or eyes that seem to bulge out.

If the thyroid is under-performing, then the most common symptom is unexpected weight gain. There may also be dry skin, frequent constipation, and an intolerance for the cold. Some people also experience a puffiness to their skin, struggle with fatigue, and be able to feel their thyroid gland because it has been enlarged. Women may see changes to their menstrual cycle.

TFT blood tests are also ordered on a frequent basis during annual exams. It will also be a component of treatment for those who have been diagnosed with a thyroid disorder. TFT screening is also performed as part of the newborn screening process in the United States.

What Do My TFT Blood Test Results Mean?

In most situations, the TFT blood test results will be communicated as being either “normal,” “low,” or “high.” In general terms, high results mean that there is the potential for an overactive thyroid. Low results would indicate that the thyroid is under-performing. Normal results, with the signs and symptoms of a thyroid disorder present, indicate that there may be a different cause for what is going on.

When a complete series of TFT blood tests is given, the combination of results will be evaluated to determine a potential interpretation and possible diagnosis. Here are some of the most common test result outcomes that are reported.

High TSH levels, but normal test results otherwise: A mild case of hypothyroidism.

High TSH levels, by low test results otherwise: Hypothyroidism.

Normal T4 and T3, but low TSH: Mild hyperthyroidism.

High T4 and/or T3 with low TSH: Hyperthyroidism.

Low TFT blood test results in all categories: Either secondary hypothyroidism or the presence of an illness not related to the thyroid gland.

High T4 and T3 with normal TSH: This is evidence of a rare resistance syndrome which is a mutation that causes the hormone receptors of the gland to decrease their hormone function.

Test results may be generalized for the purpose of reporting, but individual results can vary and must be interpreted by a medical provider. Different testing laboratories may also have varying definitions of what qualifies as a low, normal, or high result.

My Doctor Told Me That I Need a T7 Blood Test – What Is That?

The T7 blood test is one of the original tests that were used to determine the Free Thyroxine Index. It was give with a series of uptake tests that were called the “T-Uptake Methods” and was usually referred to as the FTI blood test. It is basically an estimation of how much free T4 concentration is currently present.

Because there are methods to measure T4 and T3 direction, the T7 blood test is rarely used today. You may wish to discuss this guide with your medical provider if an FTI or T7 blood test has been ordered.

Here’s What You Need to Know

If you’re concerned about the functionality of your thyroid, then understand that it is generally recommended to avoid TFT blood tests while being hospitalized or while suffering from an acute illness. This affects hormone levels and may produce false results.

The thyroid system is also considered to be a “dynamic” system within the human body. This means that there are many different circumstances which could affect the hormone levels which are detected through testing. Something as simple as an increase in the proteins that bind T4 and T3 will alter test results, even if the thyroid is producing hormones consistent.

Certain drugs, the presence of liver disease, and even becoming pregnant are also known to affect TFT blood test results.